1. Field of the Invention
The present invention relates to pneumatic jacks and in particular to those pneumatic jacks that are made from a flexible material.
2. Prior Art
The prior art shows various types of pneumatic jacks, however, in each case the use of the jack has been limited by its design. In U.S. Pat. No. 3,695,582, a pneumatic jack is shown made of a hollow, flexible material. This jack has the disadvantage of not being able to conform to the surface of the object it is supporting, nor the ground on which it is resting. This limits the safe use of the jack to level or even terrain which may not be the case when a tire needs changing. Further, the base of the jack has the same diameter as the top, limiting the possible safe height that the jack can be designed for without making the diameters extraordinarily large to prevent possible tipping.
In U.S. Pat. No. 3,743,248 a pneumatic jack is also shown utilizing rigid telescoping tubing enclosed by a bellows. This jack also has the disadvantage of having a rigid top and bottom thereby not being able to conform to any surfaces. It also is limited as to the height that it can be collapsed to by the height of the rigid tubing.
U.S. Pat. No. 3,744,756 shows an inflatable bag used for lifting vehicles. The bag is reinforced with webbing to aid in retaining its shape.
U.S. Pat. No. 3,704,189 discloses a method of making a jack and discloses a barrel shaped collapsible bag as well as a tube shape.
A lifting device using an air bag between platforms is shown in U.S. Pat. No. 3,799,504.